SEHS Topic 6: Measurement and Evaluation of Human Performance

• Can you calculate the mean and standard deviation?(must be able to perform it on a Ti-84 or similar calculator)

• Instructions: http://www.ehow.com/how_8054806_calculate-standard-deviations-ti84s.html

Outline what information error bars provide on a graph

What do 1 and 2 standard deviations say about a normally distributed data set?

• Approximately 68% to 95% of the data values fall within +/- one or two standard deviations of the mean

Explain how the standard deviation is useful

Coefficient of Variation

Deduce the significance of the difference between two sets of data using calculated t-test values

• When a t-test can be applied?:• Data should have a normal distribution (aka. a continuous

probability distribution )• every normal curve (regardless of its mean or standard

deviation) conforms to the following "rule".– About 68% of the area under the curve falls within 1 standard

deviation of the mean.– About 95% of the area under the curve falls within 2 standard

deviations of the mean.– About 99.7% of the area under the curve falls within 3 standard

deviations of the mean.)* Sample size of at least 10/data set*Used for two-tailed*Paired or unpaired data

T-test Cont’dhttp://www.ats.ucla.edu/stat/mult_pkg/faq/general/tail_tests.htm

Explain that the existence of a correlation does not establish that there is a causal relationship

between two variables

• Relationship vs cause• Specificity• There is a relationship between lung cancer and

smoking• Is smoking the cause of all lung cancers?– Strong correlation but not necessarily the cause

Proper Study Design• When measuring an individual’s fitness levels it is

important to ensure it is done as well as possible• Main factors to take into account:– Specificity (sport specific tests….ex?)

– Accuracy(technical/instrument upkeep)

– Reliability (the degree to which a measure would produce the same result from one occasion to another) – test after skill is learned completely to avoid habituation effect

– Validity(sport specific test and repititions)

Designing sport and exercise science experiments

• Cause and effect experimentation• Does taking 20g of creatine phosphate 30 minutes

before a resistance training workout produce significant improvement of one’s 1 rep max?

• What’s wrong with this design?• How can it be designed better?

PRE-TEST ---- TREATMENT W/ CP

------- POST-TEST

Here’s a hint:

EXPERIMENTAL GROUP

PRE-TEST ------- ------ POST TEST

CONTROL GROUP

PRE-TEST ------- ------- POST TEST

Made better still by adding a placebo